A number of chemical preparations suffer from a progressive deterioration of their properties over time. This deterioration is due to the effect of various physical and chemical changes caused, for example, by processes such as drying, oxidation, cross reactions and polymerization. These preparations are therefore most effective when they are prepared no more than a short time prior to their intended use. Examples of compositions which fit this description include many types of adhesives, as well as other products having a limited "shelf life", particularly materials having a medicinal effect.
Various processes have been described for obtaining, when required, a mixture of two constituent materials to form compositions of the type described above. The most convenient method to obtain such a combination is to divide the preparation into two components, wherein a first portion is in the form of a liquid which acts as a solvent and the second portion may be present as, for example, a solid dispersed in the form of a powder.
It is also known to produce various products, such as perfumes and insecticides, in an aerosol form. These aerosols may be obtained by the discharge of a gas or a supporting liquid such as nitrogen, butane or a fluorocarbon composition. This permits these products to be delivered in small doses, e.g., as a very fine spray.
Such products are often packaged in aerosol containers or bottles provided with a valve of relatively small size. The valve is operatively associated with a tubular control stem to serve as an atomizer, upon which is seated a push button of variable structure. This push button normally carries a spray nozzle for dispensing the product. Devices of this type are often utilized, for example, to contain and deliver various types of medicaments, including those most often intended for treatment of respiratory difficulties, such as those involving the bucco-pharyngile and/or pulmonary ducts.